The invention relates to a nail driving gun, more particularly to a cap assembly for covering an air release opening in a housing of the nail driving gun.
Referring to FIG. 1, a conventional nail driving gun is shown to include a gun housing 1, a cap assembly 2, a spring-loaded sealing member 4, and a pneumatically driven piston unit 40.
As illustrated, the gun housing 1 has an inner wall 11 confining a chamber 110, a nail-discharging end 111, an open end 112 that is opposite to the nail-discharging end 111 and that defines an air release opening 112xe2x80x3 which is in fluid communication with the chamber 110. The piston unit 40 is movably disposed in the chamber 110 for discharging a nail through the nail-discharging end 111 of the gun housing 1 upon introduction of a high pressure into the chamber 110. The cap assembly 2 is mounted detachably on the open end 112 of the gun housing 1 for covering the air release opening 112xe2x80x3, and includes a cover 21 that is fastened detachably to an end face of the open end 112 of the gun housing 1 via a plurality of fastener bolts 3 and a packing 22, and that is formed with a plurality of air outlets 212, and a guide 23 detachably mounted on the cover 21 via a locking screw 231. The guide 23 is formed with at least one outlet hole 232 in spatial communication with the air release opening 112xe2x80x3 through the air outlets 212 in the cover 21. The sealing member 4 is disposed sealingly and movably in the chamber 110, and is operably associated with the piston unit 40 for selectively and sealingly covering the air release opening 112xe2x80x3 in the gun housing 1.
One drawback of the aforesaid conventional nail driving gun resides in that it is inconvenient to mount and dismount the cap assembly 2 on and from the open end 112 of the gun housing 1.
Therefore, the object of this invention is to provide a cap assembly for covering an air release opening in a gun housing of a nail driving gun, which can be mounted on or dismounted from the gun housing in a convenient manner.
A pneumatically operated nail driving gun of the present invention includes a gun housing, a cap assembly, and a sealing member. The gun housing has an inner wall confining a chamber, a nail-discharging end, and an open end that is opposite to the nail-discharging end and that defines an air release opening which is in fluid communication with the chamber. The inner wall is formed with an internal thread that extends inwardly from the open end. The cap assembly is mounted detachably on the open end of the gun housing for covering the air release opening. The cap assembly includes a cylindrical body having an annular first flange portion that confines an inner space and that is formed with an external thread engaging the internal thread of the inner wall, and an annular second flange portion that is reduced coaxially from said first flange portion, that extends into the chamber and that defines a receiving space in spatial communication with the inner space. The cap assembly further includes a nut disposed coaxially within the inner space, and a plurality of ribs which extend radially from the first flange portion to connect with the nut. A cover is detachably mounted on the first flange portion for covering the inner space, and is formed with at least one air outlet which is in fluid communication with the inner space. A fastener bolt extends through the cover, and engages the nut threadedly. The sealing member is disposed movably in the chamber, and includes a cylindrical fixed sealing part, an annular sealing ring, and a movable sealing part. The fixed sealing part is coaxially disposed within the receiving space, is secured to the nut, and cooperates with the second flange portion to define a gap therebetween. The sealing ring is coaxially disposed above the fixed sealing part and abuts against the nut. The movable sealing part is slidably and sealingly inserted into the gap, has a top end formed with an abutment end face, and is movable relative to the fixed sealing part between a first position, in which the abutment end face of the movable sealing part abuts sealingly against the sealing ring so as prevent fluid communication between the chamber and the inner space, and a second position, in which the movable sealing part moves away from the sealing ring, thereby permitting release of air through the receiving space, the inner space, and the air outlet in the cover. An urging member urges the movable sealing part to the second position.